Sheraton Hanoi Hotel has carried out many technical solutions to improve the energy efficiency of the building active systems. All these solutions brought significant economic benefits for the hotel. Calculations reveal that these measures are highly profitable financially considering the payback period lower than two years, ranging from 8 months to 15 months. The most striking point for Sheraton Hanoi energy efficiency measures is that the hotel is one of the first buildings in Vietnam to install Heat Pumps and Variable Speed Drive (VSD) motors for Chilled Water Pump in the AC system. These measures bring annual savings of USD 200,000 which are considered among the most profitable measures.

Third Party verified: No
Source of information: Sheraton Hanoi
Method of data collection: interview with chief engineer, data collection via email and site visit

Building envelops:
The walls of the North-East and South-West facades consist of three layers: two 110mm brick wall layers and one 50mm Glass Wool insulation layer inside (with thermal conductivity k of 0.04 W/m.K).

The paint for the facades is yellow based on the low solar absorption coefficient of 0.44.

The windows-to-wall ratio (WWR) is 30% to reduce heat gain in the building.

Building envelop

The overall thermal transfer value (OTTV) through wall is 30W/m2, corresponding to 50% reduction compared to the requirements specified in the Energy Efficiency Building Code 2013 of Vietnam.

Day lighting:
The hotel is designed to maximise the natural light, especially in lobby area, meeting halls, and conference rooms. The estimated floorplate with daylight is 45%.

Air conditioning system:
The air conditioning system in Sheraton is the centralised water cooled chiller system. The limitations in the original system design include:
• All motors such as pumps and fans ran at constant speeds according to the maximum water flow rate and cooling load.
• Excess chilled water not used in the FCUs was returned by using by-pass loops. Energy is wasted in unnecessarily cooled water.
• The water flow rate in condenser water circuit is constant at maximum level. Therefore, wasted energy is consumed for the pump motors, fans in cooling towers and chiller system running for all the excess water.

Schematic diagram of the central air conditioning system

To improve the energy efficiency of the system, from 2005 to 2008, Sheraton Hotel had invested in 16 Variable Speed Drive (VSD) motors to control the speed of these motors according to the real cooling load. Details are as follows:

1. Chilled water system:
VSDs are installed for four 55kW chilled water pumps. The achieved results for the recorded first year are:
• Percentages of average savings: 53% – 63%
• Energy savings: 361,720 kWh/year.

Primary Chiller Water Pump

2. Condenser Water Pump:
VSDs are installed for four 22kW Condenser Water Pumps. The following figures are recorded:
• Energy saving: 33%-55%
• Total energy saved: 58,000 kWh/year

Flow rate in the original design: 20 – 76 liter/second. Upon installation of the VSDs, the flow rate is set within the range of 28 – 45 liter/second

6. Temperature control for room hotel by Digital Thermostat:
320 sets of digital thermostats are installed to improve the efficiency of the AHU system by preventing the fan from working harder than it needs to. The following figures are recorded:
• Total energy saved: 41,000kWh/ year

This practice saves 50% of the power demand for lighting or 200,000 kW/year.

8. Lighting control system:
Install photo sensors for the outdoor lighting system to turn on the lights when it gets dark and turn off the lights when the sun rises.

Building Loads:
9. Hot water supply:
Oil water boilers are replaced by 8 sets of heat pumps. The achieved benefits include:
• Diesel oil saved: 400 – 500 liter/day
• 168kW cooled air/hour is generated for the laundry room, eliminating the need for AC.
• Originally, the average temperature in Laundry is 34 – 35oC. Upon installation of Heat pump, it is reduced to 26 – 27oC.
• For every 5.6 kW electricity used, 24.5kW of heat and 22.5 kW of cooled air are generated

Schematic drawing for the water heater system is as follows:

Heat pump in Laundry Area

10. Water saving:
250 water flow reducers are installed for showers, 350 sensors for water taps. Water consumption is reduced from 22-25 liter/minute to 6-8 liter/min for water taps and to 9-11l/min for showers. Calculation shows that 20,000 m3 of water is saved annually.

Commitment to energy efficiency policies

Sheraton Hanoi has a strong policy on environmental protection and is certified with ISO 14001. The clear commitment to social responsibility and environmental protection from the top managers of the hotel is a big advantage for the implementation of energy efficiency measures.

Monitoring:

1. Monitoring system

Install Building Automation System (BAS)

This BAS will monitor the HVAC and lighting system

o control and set up necessary temperature in public area

o control timing on – off lighting system

o monitoring and management the status of each system, control whether it work in optimal status to adjust each system accordingly

BAS – The management equipment system in Hotel

2. Key card system:

The entire guest room door had been set up key card system. The electricity in room will be automatic switch when getting out key.

Strictly maintain according to the manufacturer’s schedule with good quality and is made with professional staff.

Train for technical staff operating rooms have full knowledge about the optimal operating system (for central air conditioning system, boiler) so that employees could understand and master when the equipment operating rationally wasters.

Communicate with other departments on energy saving, special attention to Housekeeping area, laundry, meeting area, restaurant .To re view and improve all process in service of Room cleaning, laundry and kitchen, stewarding, engineering… to save energy.

Regularly update information about the Energy Saving Measures latest and most feasible to apply and train for staff.